[mushbino]

It's purely tribalism at its heart. It's much easier to exploit a group if they are perceived as different. Skin color and looks are the easiest things to distinguish one group from another. It's more challenging to marginalize a group if they can be seen as just like you and me.

In the Americas, the dominant group, both financially and politically has been people with lighter skin. This is how we've been trained to think for a very long time and it persists to this day. Had history played out differently and people with dark skin did the colonizing to people with white skin, things would be different, but that's not the case.

This same thing has been done to Jews in Europe and elsewhere for a couple thousand years. These groups of people who are "different" have been used as convenient scapegoats, which we know has played a central role in civilization since the very beginning. https://en.wikipedia.org/wiki/Scapegoating

To bring it back to the US, the black population and eventually the Hispanic population have been used as scapegoats for white societies to look at as the source of their problems. It's a way of maintaining social cohesion (in the dominant group).